Acute Exercise Decreases Tribbles Homolog 3 Protein Levels in the Hypothalamus of Obese Rats.

PURPOSE: This study aims to evaluate the effects of acute exercise on tribbles homolog 3 (TRB3) protein levels and on the interaction between TRB3 and Akt proteins in the hypothalamus of obese rats. In addition, we evaluated the relationship between TRB3 and endoplasmic reticulum (ER) stress and verified whether an acute exercise session influences them.
METHODS: In the first part of the study, the rats were divided into three groups: control (lean), fed standard rodent chow; DIO, fed a high-fat diet; and DIO-EXE, fed a high-fat diet and submitted to a swimming acute exercise protocol. In the second part of the study, we used three other groups: control (lean) group receiving an intracerebroventricular (i.c.v.) infusion of vehicle, lean group receiving an i.c.v. infusion of thapsigargin, and lean group receiving an i.c.v. infusion of thapsigargin and performing an acute exercise session. Four hours after the exercise session, food intake was measured, and the hypothalamus was dissected and separated for subsequent protein analysis by immunoblotting and real-time polymerase chain reaction.
RESULTS: The acute exercise session reduced TRB3 protein levels, disrupted the interaction between TRB3 and Akt proteins, increased the phosphorylation of Foxo1, and restored the anorexigenic effects of insulin on the hypothalamus of DIO rats. Interestingly, the suppressive effects of acute exercise on TRB3 protein levels may be related, at least in part, to decreased ER stress (evaluated though pancreatic ER kinase phosphorylation and C/EBP homologous protein levels) in the hypothalamus.
CONCLUSION: Exercise-mediated reduction of hypothalamic TRB3 protein levels may be associated with reduction of ER stress. These data provide a new mechanism by which an acute exercise session improves insulin sensitivity in the hypothalamus and restores food intake control in obesity.